In general terms, wetlands are lands where saturation with water is the dominant factor determining the nature of soil development and the types of plant and animal communities living in the soil and on its surface. The single feature that most wetlands share is soil or substrate that is at least periodically saturated with or covered by water. The water creates severe physiological problems for all plants and animals except those that are adapted for life in water or in saturated soil.
---Cowardin et al, see below.
The U. S. National Fish and Wildlife Service has developed a classification code for wetlands in the United States. The initial letter identifies the system, either estuarine, riverine, lacustrine, or palustrine (e.g., “E” means estuarine). The second character is a number identifying a subsystem, except for the palustrine system, which has no subsystems. The next characters are letters identifying a class, and the final numbers identify the subclass. So, for example, “E2RB1” means estuarine, intertidal, rocky bottom consisting of bedrock.
| System | Subsystem | Class | Subclass |
|---|---|---|---|
| E= Estuarine |
1= Subtidal |
RB=Rock Bottom | 1=Bedrock 2=Rubble |
| UB=Unconsolidated bottom | 1=Cobble-gravel 2=Sand 3=Mud 4=Organic |
||
| AB=Aquatic bed | 1=Algal 3=Rooted vascular 4=Floating vascular 5=Unknown submergent 6=Unknown surface |
||
| RF=Reef | 2=Mollusc 3=Worm |
||
| OW=Open water/Unknown bottom (used on older maps) | |||
| 2= Intertidal |
AB=Aquatic bed | 1=Algal 3=Rooted vascular 4=Floating vascular 5=Unknown submergent 6=Unknown surface |
|
| RF=Reef | 2=Mollusc 3=Worm |
||
| SB=Streambed | 3=Cobble-gravel 4=Sand 5=Mud 6=Organic |
||
| RS=Rocky shore | 1=Bedrock 2=Rubble |
||
| US=Unconsolidated shore | 1=Cobble-gravel 2=Sand 3=Mud 4=Organic |
||
| EM=Emergent | 1=Persistent 2=Nonpersistent |
||
| SS=Scrub-Shrub | 1=Broad-leaved deciduous 2=Needle-leaved deciduous 3=Broad-leaved evergreen 4=Needle-leaved evergreen 5=Dead 6=Indeterminate deciduous 7=Indeterminate evergreen |
||
| FO=Forested | 1=Broad-leaved deciduous 2=Needle-leaved deciduous 3=Broad-leaved evergreen 4=Needle-leaved evergreen 5=Dead 6=Indeterminate deciduous 7=Indeterminate evergreen |
||
| Except as specifically noted, in the Riverine system any class may be used with any subsystem. | |||
| R= Riverine |
1 = Tidal |
RB=Rock bottom | 1=Bedrock 2=Rubble |
| 2 = Lower perennial |
UB=Unconsolidated bottom | 1=Cobble-gravel 2=Sand 3=Mud 4=Organic |
|
| 3 = Upper perennial |
SB=Streambed Streambed is only used with the Tidal and Intermittent subsystems, and is the only class in the Intermittent subsystem. |
1=Bedrock 2=Rubble 3=Cobble-gravel 4=Sand 5=Mud 6=Organic 7=Vegetated |
|
| 4 = Intermittent |
AB=Aquatic bed | 1=Algal 2=Aquatic Moss 3=Rooted vascular 4=Floating vascular 5=Unknown submergent 6=Unknown surface |
|
| 5 = Unknown perennial (used on older maps) |
RS=Rocky shore | 1=Bedrock 2=Rubble |
|
| US=Unconsolidated shore | 1=Cobble-gravel 2=Sand 3=Mud 4=Organic 5=Vegetated |
||
| EM=Emergent This class is only used with the Tidal and Lower Perennial subsystems |
2=Nonpersistent | ||
| OW=Open water/Unknown bottom (used on older maps) | |||
| L= Lacustrine |
1 = Limnetic |
RB=Rock bottom | 1=Bedrock 2=Rubble |
| UB=Unconsolidated Bottom | 1=Cobble-gravel 2=Sand 3=Mud 4=Organic |
||
| AB=Aquatic bed | 1=Algal 2=Aquatic Moss 3=Rooted vascular 4=Floating vascular 5=Unknown submergent 6=Unknown surface |
||
| OW=Open water/unknown bottom (used on older maps) | |||
| 2 = Littoral |
RB=Rock bottom | 1=Bedrock 2=Rubble |
|
| UB=Unconsolidated bottom | 1=Cobble-gravel 2=Sand 3=Mud 4=Organic |
||
| AB=Aquatic bed | 1=Algal 2=Aquatic Moss 3=Rooted vascular 4=Floating vascular 5=Unknown submergent 6=Unknown surface |
||
| RS=Rocky shore | 1=Bedrock 2=Rubble |
||
| US=Unconsolidated shore | 1=Cobble-gravel 2=Sand 3=Mud 4=Organic 5=Vegetated |
||
| EM=Emergent |
2=Nonpersistent | ||
| OW=Open water/unknown bottom (used on older maps) | |||
| P = Palustrine |
RB=Rock bottom | 1=Bedrock 2=Rubble |
|
| UB=Unconsolidated bottom | 1=Cobble-gravel 2=Sand 3=Mud 4=Organic |
||
| AB=Aquatic bed | 1=Algal 2=Aquatic Moss 3=Rooted vascular 4=Floating vascular 5=Unknown submergent 6=Unknown surface |
||
| US=Unconsolidated shore | 1=Cobble-gravel 2=Sand 3=Mud 4=Organic 5=Vegetated |
||
| ML=Moss-Lichen | 1=Moss 2=Lichen |
||
| EM=Emergent | 1=Persistent 2=Nonpersistent |
||
| SS=Scrub-Shrub | 1=Broad-leaved deciduous 2=Needle-leaved deciduous 3=Broad-leaved evergreen 4=Needle-leaved evergreen 5=Dead 6=Indeterminate deciduous 7=Indeterminate evergreen |
||
| FO=Forested | 1=Broad-leaved deciduous 2=Needle-leaved deciduous 3=Broad-leaved evergreen 4=Needle-leaved evergreen 5=Dead 6=Indeterminate deciduous 7=Indeterminate evergreen |
||
| OW=Open water/unknown bottom (used on older maps) | |||
If you have a code and want to know its meaning, even including plant species, an interactive page detailing the characteristics for any code can be accessed by going to www.nwi.fws.gov and clicking on “NWI Codes Definition”.
The publication on which the code is based, Classification of Wetlands and Deepwater Habitats of the United States, by Cowardin, Carter, Golet and LaRoe, is also available as PDF files at wetlands.fws.gov/Pubs_Reports/Class_Manual/class_titlepg.htm
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Last revised: 28 January 2010.